Remove generated directories with 100s of files.

client/dom/generated/src/frog/WorkerContext.dart

-
-class _WorkerContextJs extends _DOMTypeJs implements WorkerContext native "*WorkerContext" {
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-  static final int PERSISTENT = 1;
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-  static final int TEMPORARY = 0;
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-  final _WorkerLocationJs location;
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-  final _WorkerNavigatorJs navigator;
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-  EventListener onerror;
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-  final _WorkerContextJs self;
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-  final _IDBFactoryJs webkitIndexedDB;
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-  final _NotificationCenterJs webkitNotifications;
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-  void addEventListener(String type, EventListener listener, [bool useCapture = null]) native;
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-  void clearInterval(int handle) native;
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-  void clearTimeout(int handle) native;
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-  void close() native;
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-  bool dispatchEvent(_EventJs evt) native;
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-  void importScripts() native;
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-  _DatabaseJs openDatabase(String name, String version, String displayName, int estimatedSize, [DatabaseCallback creationCallback = null]) native;
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-  _DatabaseSyncJs openDatabaseSync(String name, String version, String displayName, int estimatedSize, [DatabaseCallback creationCallback = null]) native;
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-  void removeEventListener(String type, EventListener listener, [bool useCapture = null]) native;
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-  int setInterval(TimeoutHandler handler, int timeout) native;
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-  int setTimeout(TimeoutHandler handler, int timeout) native;
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-  void webkitRequestFileSystem(int type, int size, [FileSystemCallback successCallback = null, ErrorCallback errorCallback = null]) native;
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-  _DOMFileSystemSyncJs webkitRequestFileSystemSync(int type, int size) native;
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-  _EntrySyncJs webkitResolveLocalFileSystemSyncURL(String url) native;
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-  void webkitResolveLocalFileSystemURL(String url, [EntryCallback successCallback = null, ErrorCallback errorCallback = null]) native;
-}